[patch] dynamic nr online cpus

[Jes Sorensen <jes@sgi.com>]

[-- Attachment #1: Type: text/plain, Size: 248 bytes --]

Hi,

Working on allowing larger max vcpus I'd like to put in this patch that
calculates the number of online cpus. It's a building block for allowing
the larger number of max vcpus without crippling performance for the
smaller cases.

Cheers,
Jes


[-- Attachment #2: 5000-kvm-ia64-nr-online-vcpu.patch --]
[-- Type: text/plain, Size: 3508 bytes --]

Account for number of online cpus and use that in loops iterating over
the list of vpus. This patch is a building block, in the work to allow
for larger max number of vcpus.

A copy of the number of online cpus is stored in vcpu 0's private data
area to allow the number to be visible from the KVM module.

Signed-off-by: Jes Sorensen <jes@sgi.com>

---
 arch/ia64/include/asm/kvm_host.h |    3 +++
 arch/ia64/kvm/kvm-ia64.c         |   20 ++++++++++++++++----
 arch/ia64/kvm/vcpu.c             |    2 +-
 3 files changed, 20 insertions(+), 5 deletions(-)

Index: linux-2.6.git/arch/ia64/include/asm/kvm_host.h
===================================================================
--- linux-2.6.git.orig/arch/ia64/include/asm/kvm_host.h
+++ linux-2.6.git/arch/ia64/include/asm/kvm_host.h
@@ -377,6 +377,7 @@
 	int last_run_cpu;
 	int vmm_tr_slot;
 	int vm_tr_slot;
+	int online_cpus;
 
 #define KVM_MP_STATE_RUNNABLE          0
 #define KVM_MP_STATE_UNINITIALIZED     1
@@ -470,6 +471,8 @@
 	unsigned long	metaphysical_rr4;
 	unsigned long	vmm_init_rr;
 
+	int		online_cpus;
+
 	struct kvm_ioapic *vioapic;
 	struct kvm_vm_stat stat;
 	struct kvm_sal_data rdv_sal_data;
Index: linux-2.6.git/arch/ia64/kvm/kvm-ia64.c
===================================================================
--- linux-2.6.git.orig/arch/ia64/kvm/kvm-ia64.c
+++ linux-2.6.git/arch/ia64/kvm/kvm-ia64.c
@@ -316,7 +316,7 @@
 	union ia64_lid lid;
 	int i;
 
-	for (i = 0; i < KVM_MAX_VCPUS; i++) {
+	for (i = 0; i < kvm->arch.online_cpus; i++) {
 		if (kvm->vcpus[i]) {
 			lid.val = VCPU_LID(kvm->vcpus[i]);
 			if (lid.id == id && lid.eid == eid)
@@ -390,7 +390,7 @@
 
 	call_data.ptc_g_data = p->u.ptc_g_data;
 
-	for (i = 0; i < KVM_MAX_VCPUS; i++) {
+	for (i = 0; i < kvm->arch.online_cpus; i++) {
 		if (!kvm->vcpus[i] || kvm->vcpus[i]->arch.mp_state ==
 						KVM_MP_STATE_UNINITIALIZED ||
 					vcpu == kvm->vcpus[i])
@@ -825,6 +825,8 @@
 		return ERR_PTR(-ENOMEM);
 	kvm_init_vm(kvm);
 
+	kvm->arch.online_cpus = 0; /* xxx hack me harder xxx */
+
 	return kvm;
 
 }
@@ -1186,7 +1188,7 @@
 
 		/*Initialize itc offset for vcpus*/
 		itc_offset = 0UL - ia64_getreg(_IA64_REG_AR_ITC);
-		for (i = 0; i < KVM_MAX_VCPUS; i++) {
+		for (i = 0; i < kvm->arch.online_cpus; i++) {
 			v = (struct kvm_vcpu *)((char *)vcpu +
 					sizeof(struct kvm_vcpu_data) * i);
 			v->arch.itc_offset = itc_offset;
@@ -1320,6 +1322,16 @@
 		goto fail;
 	}
 
+	kvm->arch.online_cpus++;
+	/*
+	 * For vcpu 0, kvm->vcpus hasn't been assigned yet, special case it
+	 */
+	if (!id)
+		vcpu->arch.online_cpus = kvm->arch.online_cpus;
+	else
+		kvm->vcpus[0]->arch.online_cpus = kvm->arch.online_cpus;
+
+	printk(KERN_INFO "arch.online_cpus %i\n", kvm->arch.online_cpus);
 	return vcpu;
 fail:
 	return ERR_PTR(r);
@@ -1766,7 +1778,7 @@
 	struct kvm_vcpu *lvcpu = kvm->vcpus[0];
 	int i;
 
-	for (i = 1; i < KVM_MAX_VCPUS; i++) {
+	for (i = 1; i < kvm->arch.online_cpus; i++) {
 		if (!kvm->vcpus[i])
 			continue;
 		if (lvcpu->arch.xtp > kvm->vcpus[i]->arch.xtp)
Index: linux-2.6.git/arch/ia64/kvm/vcpu.c
===================================================================
--- linux-2.6.git.orig/arch/ia64/kvm/vcpu.c
+++ linux-2.6.git/arch/ia64/kvm/vcpu.c
@@ -816,7 +816,7 @@
 	unsigned long vitv = VCPU(vcpu, itv);
 
 	if (vcpu->vcpu_id == 0) {
-		for (i = 0; i < KVM_MAX_VCPUS; i++) {
+		for (i = 0; i < vcpu->arch.online_cpus; i++) {
 			v = (struct kvm_vcpu *)((char *)vcpu +
 					sizeof(struct kvm_vcpu_data) * i);
 			VMX(v, itc_offset) = itc_offset;